1. Technical Field
The present invention relates to a UV curable ink jet recording ink composition, an ink container containing the ink composition, and an inkjet recording apparatus.
2. Related Art
Various techniques are applied to recording processes for forming images on a recording medium, such as paper, according to image data signals. Among such techniques is an ink jet technique in which images are formed directly on a recording medium by ejecting an ink only onto desired image portions, using an inexpensive apparatus. In the ink jet technique, inks are efficiently used, and accordingly running cost can be reduced. In addition, little noise is produced when the ink jet technique is used, and the ink jet technique is thus advantageous as a recording method.
In order to form an image having high fastness to water, solvents, rubbing and so forth on the surface of a recording medium, UV curable ink jet recording inks that can be cured by being irradiated with UV radiation have been used in an ink jet recording method in recent years.
For example, JP-A-2007-138070 discloses an ink jet ink containing a coloring material, water, and an active energy radiation-crosslinkable polymer that includes a hydrophilic main chain having a plurality of side chains and can form a cross link between the side chains by being irradiated with active energy radiation. In this ink, the dissolved oxygen content is 0.05 to 1.8 ppm at 25° C. According to the disclosure, the ink can be easily discharged and can form highly glossy images having high rub fastness without bleeding (paragraph 0023 in JPA-2007-138070).
For example, JP-A-2004-196936 discloses a UV curable ink jet ink containing a water-soluble solvent, and at least a coloring material, a UV polymerizable compound and a photopolymerization initiator in the water-soluble solvent, and having a dissolved oxygen content of 0.1 to 2 ppm at 25° C. According to this disclosure, the ink can be stably discharged over a long time (paragraph 0017 and 0019 in JP-A-2004-196936)).
However, the inks disclosed in the above-cited patent documents are undesirably inferior in at least any of curability, storage stability and ejection stability.